A wide variety of asynchronous communication devices are conventionally connected to computer systems. Generally, this has been done using an integrated chip device known as a UART, an acronym for Universal Asynchronous Receiver Transmitter.
Over time, UARTs have appeared in three functional types, namely unbuffered UARTs, buffered UARTs, and DMA UARTs, the strengths and weaknesses of which for use in high speed communication are discussed below.